******************************************************************************************** SI/USGS Weekly Volcanic Activity Report 21-27 October 2009 From: "Sally Kuhn Sennert " <KUHNS@xxxxxx> ******************************************************************************************** SI/USGS Weekly Volcanic Activity Report 21-27 October 2009 Sally Kuhn Sennert - Weekly Report Editor kuhns@xxxxxx URL: http://www.volcano.si.edu/reports/usgs/ New Activity/Unrest: | Chaitén, Southern Chile | Ebeko, Paramushir Island | Kliuchevskoi, Central Kamchatka (Russia) | Mayon, Luzon | Nevado del Huila, Colombia | Reventador, Ecuador | Soufrière Hills, Montserrat Ongoing Activity: | Batu Tara, Komba Island (Indonesia) | Colima, México | Dukono, Halmahera | Fuego, Guatemala | Karymsky, Eastern Kamchatka | Kilauea, Hawaii (USA) | Pacaya, Guatemala | Rabaul, New Britain | Sakura-jima, Kyushu | Santa María, Guatemala | Shiveluch, Central Kamchatka (Russia) The Weekly Volcanic Activity Report is a cooperative project between the Smithsonian's Global Volcanism Program and the US Geological Survey's Volcano Hazards Program. Updated by 2300 UTC every Wednesday, notices of volcanic activity posted on these pages are preliminary and subject to change as events are studied in more detail. This is not a comprehensive list of all of Earth's volcanoes erupting during the week, but rather a summary of activity at volcanoes that meet criteria discussed in detail in the "Criteria and Disclaimers" section. Carefully reviewed, detailed reports on various volcanoes are published monthly in the Bulletin of the Global Volcanism Network. Note: Many news agencies do not archive the articles they post on the Internet, and therefore the links to some sources may not be active. To obtain information about the cited articles that are no longer available on the Internet contact the source. New Activity/Unrest CHAITEN Southern Chile 42.833°S, 72.646°W; summit elev. 1122 m SERNAGEOMIN reported that Chaitén's lava-dome complex continued to grow during 1-15 October. Steam from the E part of the complex and ash-and-steam plumes from the center were seen on clear days using the web camera, S of the volcano. Small emissions originated from numerous areas. An explosion on 14 October produced a dense ash cloud that drifted W. The Alert Level remained at Red. Based on web camera views, the Buenos Aires VAAC reported continuous emissions on 21 October. Plumes rose to altitudes of 1.8-2.4 km (6,000-8,000 ft) a.s.l. and drifted SSE. Geologic Summary. Chaitén is a small, glacier-free caldera with a Holocene lava dome located 10 km NE of the town of Chaitén on the Gulf of Corcovado. A pyroclastic-surge and pumice deposit considered to originate from the eruption that formed the elliptical 2.5 x 4 km wide summit caldera was dated at about 9400 years ago. A rhyolitic, 962-m-high obsidian lava dome occupies much of the caldera floor. Obsidian cobbles from this dome found in the Blanco River are the source of prehistorical artifacts from archaeological sites along the Pacific coast as far as 400 km away from the volcano to the north and south. The caldera is breached on the SW side by a river that drains to the bay of Chaitén, and the high point on its southern rim reaches 1122 m. Sources: Servicio Nacional de Geología y Minería (SERNAGEOMIN) http://www.sernageomin.cl/, Buenos Aires Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AG/messages.html EBEKO Paramushir Island 50.68°N, 156.02°E; summit elev. 1156 m Based on analyses of satellite imagery, the Tokyo VAAC reported that on 26 October a possible eruption plume from Ebeko rose to an altitude of 8.8 km (29,000 ft) a.s.l. and drifted E. Emissions continued the next day. Geologic Summary. The flat-topped summit of the central cone of Ebeko volcano, one of the most active in the Kuril Islands, occupies the northern end of Paramushir Island. Three summit craters located along a SSW-NNE line form Ebeko volcano proper, at the northern end of a complex of five volcanic cones. The eastern part of the southern crater of Ebeko contains strong solfataras and a large boiling spring. The central crater of Ebeko is filled by a lake about 20 m deep whose shores are lined with steaming solfataras; the northern crater lies across a narrow, low barrier from the central crater and contains a small, cold crescentic lake. Historical activity, recorded since the late-18th century, has been restricted to small-to-moderate explosive eruptions from the summit craters. Intense fumarolic activity occurs in the summit craters of Ebeko, on the outer flanks of the cone, and in lateral explosion craters. Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html KLIUCHEVSKOI Central Kamchatka (Russia) 56.057°N, 160.638°E; summit elev. 4835 m KVERT reported that during 16-23 October seismic activity from Kliuchevskoi was above background levels. Satellite imagery revealed a daily thermal anomaly at the volcano. During 16 and 18-22 October, Strombolian activity ejected tephra 500 m above the crater and fumarolic plumes were noted. The Level of Concern Color Code remained at Orange. Geologic Summary. Kliuchevskoi is Kamchatka's highest and most active volcano. Since its origin about 7,000 years ago, the beautifully symmetrical, 4,835-m-high basaltic stratovolcano has produced frequent moderate-volume explosive and effusive eruptions without major periods of inactivity. More than 100 flank eruptions, mostly on the NE and SE flanks of the conical volcano between 500 m and 3,600 m elevation, have occurred during the past 3,000 years. The morphology of its 700-m-wide summit crater has been frequently modified by historical eruptions, which have been recorded since the late-17th century. Historical eruptions have originated primarily from the summit crater, but have also included major explosive and effusive events from flank craters. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php MAYON Luzon 13.257°N, 123.685°E; summit elev. 2462 m PHIVOLCS reported that on 28 October a minor ash explosion from Mayon produced a brownish ash plume that rose 600 m above the crater and drifted NE. The Alert Level remained at 2 (on a scale of 0-5). The 7-km Extended Danger Zone (EDZ) on the SE flank and the 6-km Permanent Danger Zone (PDZ) in all other areas remained in effect. Geologic Summary. Beautifully symmetrical Mayon volcano, which rises to 2,462 m above the Albay Gulf, is the Philippines' most active volcano. The structurally simple volcano has steep upper slopes that average 35-40° and is capped by a small summit crater. The historical eruptions of this basaltic-andesitic volcano date back to 1616 and range from Strombolian to basaltic Plinian. Eruptions occur predominately from the central conduit and have also produced lava flows that travel far down the flanks. Pyroclastic flows and mudflows have commonly swept down many of the approximately 40 ravines that radiate from the summit and have often devastated populated lowland areas. Mayon's most violent eruption, in 1814, killed more than 1,200 people and devastated several towns. Eruptions that began in February 2000 led PHIVOLCS to recommend on 23 February 2000 the evacuation of people within a radius of 7 km from the summit in the SE and within a 6 km radius for the rest of the volcano. Source: Philippine Institute of Volcanology and Seismology (PHIVOLCS) http://www.phivolcs.dost.gov.ph/ NEVADO DEL HUILA Colombia 2.93°N, 76.03°W; summit elev. 5364 m The Washington VAAC reported a possible eruption from Nevado del Huila on 20 October. An ash plume was seen on satellite imagery drifting 45 km S and INGEOMINAS had reported increased seismicity. Another ash cloud was seen on satellite imagery drifting S later that day. Based on web camera views, INGEOMINAS reported that on 21 October continuous gas emissions rose from Nevado del Huila and pulses of ash emissions produced plumes that drifted E. Observations during an overflight on 23 October revealed that gas-and-ash emissions originated from two locations. The area of greater discharge was between Pico Central and the lava dome, while fewer emissions came from the fissure that opened in April 2007, NE of Pico Central. Lava-dome growth was concentrated on the N end of the lava dome, an area also exhibiting a thermal anomaly detected with a thermal imaging camera. The Alert Level remained at II (Orange; "probable eruption in term of days or weeks"). Ashfall and sulfur odors were reported in several inhabited areas on 23 and 24 October. Based on analyses of satellite imagery and information from INGEOMINAS, the Washington VAAC reported that on 24 October an eruption produced an ash plume that rose to an altitude of 9.1 km (30,000 ft) a.s.l. and drifted WSW. During 25-26 October, thermal anomalies were seen on satellite imagery. A plume drifted WSW on 25 October and a gas-and-ash plume drifted 90 km NW and SW on 26 October. Geologic Summary. Nevado del Huila, the highest active volcano in Colombia, is an elongated N-S-trending volcanic chain mantled by a glacier icecap. The andesitic-dacitic volcano was constructed within a 10-km-wide caldera. Volcanism at Nevado del Huila has produced six volcanic cones whose ages in general migrated from south to north. Two glacier-free lava domes lie at the southern end of the Huila volcanic complex. The first historical eruption from this little known volcano took place in the 16th century. Two persistent steam columns rise from the central peak, and hot springs are also present. Sources: Instituto Colombiano de Geología y Minería (INGEOMINAS) http://www.ingeominas.gov.co//, Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html REVENTADOR Ecuador 0.077°S, 77.656°W; summit elev. 3562 m The IG reported that on 21 October, steam-and-gas plumes from Reventador with little to no ash content rose 2-4 km above the crater and drifted NW, W, and S. An explosion that day ejected incandescent material from the crater; blocks rolled down the flanks. On 22 October, a few explosions generated ash-and-steam plumes with little to no ash content that rose 4 km and drifted NW, E, and SE. Observations during an overflight revealed a small lava flow on the N flank and a larger flow with four branches on the S flank. Some of the base of the lava dome had been removed, and small spines were present, especially on the S side of the dome. Thermal images revealed that material in the crater was 400 degrees Celsius and the lava-flow fronts were 250 degrees Celsius. Cloudy weather prevented visual observations during 23-26 October. Roaring noises were heard on 25 October. Geologic Summary. Reventador is the most frequently active of a chain of Ecuadorian volcanoes in the Cordillera Real, well E of the principal volcanic axis. It is a forested stratovolcano that rises above the remote jungles of the western Amazon basin. A 3-km-wide caldera breached to the E was formed by edifice collapse and is partially filled by a young, unvegetated stratovolcano that rises about 1,300 m above the caldera floor. Reventador has been the source of numerous lava flows as well as explosive eruptions that were visible from Quito in historical time. Frequent lahars in this region of heavy rainfall have constructed a debris plain on the eastern floor of the caldera. Source: Instituto Geofísico-Escuela Politécnica Nacional (IG) http://www.igepn.edu.ec/ SOUFRIERE HILLS Montserrat 16.72°N, 62.18°W; summit elev. 915 m MVO reported that during 16-25 October activity from the Soufrière Hills lava dome was at a high level; a new lava dome first reported on 9 October continued to grow in the summit region on the W side. The new dome was considerably higher than the older lava dome that is to the E. Seismicity was high and cycles of low-level tremor occurred at regular intervals. Several pyroclastic flows descended the White River to the S and reached the sea. Small pyroclastic flows traveled NE down Tuitts Ghaut and W down Gages valley, but seldom to the N down Tyers Ghaut or E down the Tar River valley. Rockfalls occurred on the S and SE flanks of the lava dome. Multiple ashfalls were reported in inhabited areas, and lahars traveled NW down the Belham valley. During 23-25 October, seismicity decreased and ash plumes generated by pyroclastic flows drifted W. The Hazard Level remained at 3. Geologic Summary. The complex dominantly andesitic Soufrière Hills volcano occupies the southern half of the island of Montserrat. The summit area consists primarily of a series of lava domes emplaced along an ESE-trending zone. English's Crater, a 1-km-wide crater breached widely to the E, was formed during an eruption about 4,000 years ago in which the summit collapsed, producing a large submarine debris avalanche. Block-and-ash flow and surge deposits associated with dome growth predominate in flank deposits at Soufrière Hills. Non-eruptive seismic swarms occurred at 30-year intervals in the 20th century, but with the exception of a 17th-century eruption that produced the Castle Peak lava dome, no historical eruptions were recorded on Montserrat until 1995. Long-term small-to-moderate ash eruptions beginning in that year were later accompanied by lava-dome growth and pyroclastic flows that forced evacuation of the southern half of the island and ultimately destroyed the capital city of Plymouth, causing major social and economic disruption. Source: Montserrat Volcano Observatory (MVO) http://www.mvo.ms/ Ongoing Activity BATU TARA Komba Island (Indonesia) 7.792°S, 123.579°E; summit elev. 748 m Based on analyses of satellite imagery, the Darwin VAAC reported that on 27 October ash plumes from Batu Tara were seen drifting 65 km W and NW at an altitude of 2.1 km (7,000 ft) a.s.l. Geologic Summary. The small isolated island of Batu Tara in the Flores Sea about 50 km north of Lembata (formerly Lomblen) Island contains a scarp on the eastern side similar to the Sciara del Fuoco of Italy's Stromboli volcano. Vegetation covers the flanks of Batu Tara to within 50 m of the 748-m-high summit. Batu Tara lies north of the main volcanic arc and is noted for its potassic leucite-bearing basanitic and tephritic rocks. The first historical eruption from Batu Tara, during 1847-52, produced explosions and a lava flow. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html COLIMA México 19.514°N, 103.62°W; summit elev. 3850 m The government of the state of Colima reported that on 22 October a gray plume from Colima rose to an altitude of 4 km (13,100 ft) a.s.l. and drifted SW. The next day, white plumes drifted NE and N, one at an altitude of 4.2 km (13,800 ft) a.s.l. Geologic Summary. The Colima volcanic complex is the most prominent volcanic center of the western Mexican Volcanic Belt. It consists of two southward-younging volcanoes, Nevado de Colima (the 4,320 m high point of the complex) on the N and the historically active Volcán de Colima on the S. Volcán de Colima (also known as Volcán Fuego) is a youthful stratovolcano constructed within a 5-km-wide caldera, breached to the S, that has been the source of large debris avalanches. Major slope failures have occurred repeatedly from both the Nevado and Colima cones, and have produced a thick apron of debris-avalanche deposits on three sides of the complex. Frequent historical eruptions date back to the 16th century. Occasional major explosive eruptions (most recently in 1913) have destroyed the summit and left a deep, steep-sided crater that was slowly refilled and then overtopped by lava dome growth. Source: Gobierno del Estado de Colima http://www.colima-estado.gob.mx/2006/seguridad/indvolcan.php DUKONO Halmahera 1.68°N, 127.88°E; summit elev. 1335 m Based on analyses of satellite imagery, the Darwin VAAC reported that during 22-23 and 26-27 October ash plumes from Dukono rose to altitudes of 2.1-2.4 km (7,000-8,000 ft) a.s.l. and drifted 45-95 km NE and E. Geologic Summary. Reports from this remote volcano in northernmost Halmahera are rare, but Dukono has been one of Indonesia's most active volcanoes. More-or-less continuous explosive eruptions, sometimes accompanied by lava flows, occurred from 1933 until at least the mid-1990s, when routine observations were curtailed. During a major eruption in 1550, a lava flow filled in the strait between Halmahera and the N-flank cone of Gunung Mamuya. Dukono is a complex volcano presenting a broad, low profile with multiple summit peaks and overlapping craters. Malupang Wariang, 1 km SW of Dukono's summit crater complex, contains a 700 x 570 m crater that has also been active during historical time. Source: Darwin Volcanic Ash Advisory Centre (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/AU/messages.html FUEGO Guatemala 14.473°N, 90.880°W; summit elev. 3763 m Based on analyses of satellite imagery and a pilot observation, the Washington VAAC reported that on 20 October an apparent ash plume from Fuego drifted SSW. On 21 October, multiple ash emissions resulted in an ash cloud that drifted 55 km S. Emissions were also reported the next day. On 26 October, a diffuse gas-and-ash plume drifted W. That same day, INSIVUMEH reported that explosions produced plumes that rose to altitudes of 4.4-4.8 km (14,400-15,700 ft) a.s.l. and drifted 10 km S and SW. Ash fell downwind, rumbling and degassing sounds were reported, and avalanches of blocks descended the flanks. On 27 October, a few ash clouds seen on satellite imagery drifted 90 km NW. Geologic Summary. Volcán Fuego, one of Central America's most active volcanoes, is one of three large stratovolcanoes overlooking Guatemala's former capital, Antigua. The scarp of an older edifice, Meseta, lies between 3,763-m-high Fuego and its twin volcano to the N, Acatenango. Construction of Meseta volcano continued until the late Pleistocene or early Holocene, after which growth of the modern Fuego volcano continued the southward migration of volcanism that began at Acatenango. Frequent vigorous historical eruptions have been recorded at Fuego since the onset of the Spanish era in 1524, and have produced major ashfalls, along with occasional pyroclastic flows and lava flows. The last major explosive eruption from Fuego took place in 1974, producing spectacular pyroclastic flows visible from Antigua. Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/, Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html KARYMSKY Eastern Kamchatka 54.05°N, 159.45°E; summit elev. 1536 m KVERT reported that seismic activity at Karymsky was above background levels during 16-23 October and possibly indicated that ash plumes rose to an altitude of 3.9 km (12,800 ft) a.s.l. The Level of Concern Color Code remained at Orange. Based on information from KEMSD, the Tokyo VAAC reported that eruptions during 24-25 October produced plumes that rose to altitudes of 3.4-3.7 km (11,000-12,000 ft) a.s.l. Ash was not identified on satellite imagery. Geologic Summary. Karymsky, the most active volcano of Kamchatka's eastern volcanic zone, is a symmetrical stratovolcano constructed within a 5-km-wide caldera that formed about 7,600-7,700 radiocarbon years ago. Construction of the Karymsky stratovolcano began about 2,000 years later. The latest eruptive period began about 500 years ago, following a 2,300-year quiescence. Much of the cone is mantled by lava flows less than 200 years old. Historical eruptions have been Vulcanian or Vulcanian-Strombolian with moderate explosive activity and occasional lava flows from the summit crater. Most seismicity preceding Karymsky eruptions has originated beneath Akademia Nauk caldera, which is located immediately S of Karymsky volcano and erupted simultaneously with Karymsky in 1996. Sources: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php, Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html KILAUEA Hawaii (USA) 19.421°N, 155.287°W; summit elev. 1222 m During 21-27 October, HVO reported that lava flowed SE from underneath Kilauea's Thanksgiving Eve Breakout (TEB) and rootless shield complex through a lava tube system, reaching the Waikupanaha ocean entry on most days. Thermal anomalies detected in satellite images and visual observations revealed active surface lava flows. For a few days an active lava flow advanced on the coastal plain, burning vegetation and pavement along the former Kalapana access road. Intermittent incandescence was seen from the Pu'u 'O'o crater floor and an East wall vent. The vent in Halema'uma'u crater continued to produce a diffuse white plume that drifted SW. Incandescence originated from occasionally spattering holes from a surface inside the vent cavity. Preliminary measurements indicated that the sulfur dioxide emission rate at the summit remained elevated; 560-1,400 tonnes per day was measured during 21-22 and 26 October. The 2003-2007 average rate was 140 tonnes per day. Geologic Summary. Kilauea, one of five coalescing volcanoes that comprise the island of Hawaii, is one of the world's most active volcanoes. Eruptions at Kilauea originate primarily from the summit caldera or along one of the lengthy E and SW rift zones that extend from the caldera to the sea. About 90% of the surface of Kilauea is formed of lava flows less than about 1,100 years old; 70% of the volcano's surface is younger than 600 years. A long-term eruption from the East rift zone that began in 1983 has produced lava flows covering more than 100 sq km, destroying nearly 200 houses and adding new coastline to the island. Source: US Geological Survey Hawaiian Volcano Observatory (HVO) http://hvo.wr.usgs.gov/ PACAYA Guatemala 14.381°N, 90.601°W; summit elev. 2552 m On 23 and 26 October, INSIVUMEH reported that white and blue plumes from Pacaya's MacKenney cone rose 50-150 m and drifted W and SW. Multiple lava flows on the S flank traveled 75-350 m SSW. Geologic Summary. Eruptions from Pacaya, one of Guatemala's most active volcanoes, are frequently visible from Guatemala City, the nation's capital. Pacaya is a complex volcano constructed on the southern rim of the 14 x 16 km Pleistocene Amatitlan caldera. A cluster of dacitic lava domes occupies the caldera floor. The Pacaya massif includes the Cerro Grande lava dome and a younger volcano to the SW. Collapse of Pacaya volcano about 1,100 years ago produced a debris-avalanche deposit that extends 25 km onto the Pacific coastal plain and left an arcuate somma rim inside which the modern Pacaya volcano (MacKenney cone) grew. During the past several decades, activity at Pacaya has consisted of frequent Strombolian eruptions with intermittent lava flow extrusion on the flanks of MacKenney cone, punctuated by occasional larger explosive eruptions. Source: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/ RABAUL New Britain 4.271°S, 152.203°E; summit elev. 688 m RVO reported that during 16-22 October diffuse white plumes and gray ash plumes rose from Rabaul caldera's Tavurvur cone; ash plumes rose 700 m above the crater. Ashfall was reported in areas to the NW. Geologic Summary. The low-lying Rabaul caldera on the tip of the Gazelle Peninsula at the NE end of New Britain forms a broad sheltered harbor. The outer flanks of the 688-m-high asymmetrical pyroclastic shield volcano are formed by thick pyroclastic-flow deposits. The 8 x 14 km caldera is widely breached on the E, where its floor is flooded by Blanche Bay. Two major Holocene caldera-forming eruptions at Rabaul took place as recently as 3,500 and 1,400 years ago. Three small stratovolcanoes lie outside the northern and NE caldera rims. Post-caldera eruptions built basaltic-to-dacitic pyroclastic cones on the caldera floor near the NE and western caldera walls. Several of these, including Vulcan cone, which was formed during a large eruption in 1878, have produced major explosive activity during historical time. A powerful explosive eruption in 1994 occurred simultaneously from Vulcan and Tavurvur volcanoes and forced the temporary abandonment of Rabaul city. Source: Rabaul Volcano Observatory (RVO) SAKURA-JIMA Kyushu 31.585°N, 130.657°E; summit elev. 1117 m Based on information from JMA, the Tokyo VAAC reported that explosions from Sakura-jima during 21-22, 24-25, and 27-28 October produced plumes that rose to altitudes of 1.5-2.4 km (5,000-8,000 ft) a.s.l. Some plumes drifted W, SW, S, and SE. Geologic Summary. Sakura-jima, one of Japan's most active volcanoes, is a post-caldera cone of the Aira caldera at the northern half of Kagoshima Bay. Eruption of the voluminous Ito pyroclastic flow was associated with the formation of the 17 x 23-km-wide Aira caldera about 22,000 years ago. The construction of Sakura-jima began about 13,000 years ago and built an island that was finally joined to the Osumi Peninsula during the major explosive and effusive eruption of 1914. Activity at the Kita-dake summit cone ended about 4,850 years ago, after which eruptions took place at Minami-dake. Frequent historical eruptions, recorded since the 8th century, have deposited ash on Kagoshima, one of Kyushu's largest cities, located across Kagoshima Bay only 8 km from the summit. The largest historical eruption took place during 1471-76. Source: Tokyo Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/OTH/JP/messages.html SANTA MARIA Guatemala 14.756°N, 91.552°W; summit elev. 3772 m Based on analyses of satellite imagery, the Washington VAAC reported that on 22 October multiple ash plumes from Santa María's Santiaguito lava dome complex drifted less than 20 km SW. On 23 and 26 October, INSIVUMEH reported that explosions produced ash plumes that rose above Caliente dome to altitudes of 3-3.3 km (10,000-10,800 ft) a.s.l. The plumes drifted W and SE and caused ashfall in areas downwind. Avalanches descended the SW flank of the dome. Degassing sounds resembling airplane engines were heard. Geologic Summary. Symmetrical, forest-covered Santa María volcano is one of a chain of large stratovolcanoes that rises dramatically above the Pacific coastal plain of Guatemala. The stratovolcano has a sharp-topped, conical profile that is cut on the SW flank by a large, 1-km-wide crater, which formed during a catastrophic eruption in 1902 and extends from just below the summit to the lower flank. The renowned Plinian eruption of 1902 followed a long repose period and devastated much of SW Guatemala. The large dacitic Santiaguito lava-dome complex has been growing at the base of the 1902 crater since 1922. Compound dome growth at Santiaguito has occurred episodically from four westward-younging vents, accompanied by almost continuous minor explosions and periodic lava extrusion, larger explosions, pyroclastic flows, and lahars. Sources: Instituto Nacional de Sismologia, Vulcanologia, Meteorologia, e Hidrologia (INSIVUMEH) http://www.insivumeh.gob.gt/, Washington Volcanic Ash Advisory Center (VAAC) http://www.ssd.noaa.gov/VAAC/messages.html SHIVELUCH Central Kamchatka (Russia) 56.653°N, 161.360°E; summit elev. 3283 m KVERT reported that during 16-23 October seismic activity from Shiveluch was above background levels and possibly indicated that ash plumes rose to an altitude of 4.5 km (14,800 ft) a.s.l. Analyses of satellite imagery revealed a large thermal anomaly over the lava dome. According to video camera data and visual observations, multiple hot avalanches traveled down the lava dome. Deposits on the SE flank from a small pyroclastic flow were noted. Fumarolic plumes rose to altitudes of 2.8-5 km (9,200-16,400 ft) a.s.l. during 16, 18-20, and 22 October. The Level of Concern Color Code remained at Orange. Geologic Summary. The high, isolated massif of Shiveluch volcano (also spelled Sheveluch) rises above the lowlands NNE of the Kliuchevskaya volcano group and forms one of Kamchatka's largest and most active volcanoes. The currently active Molodoy Shiveluch lava-dome complex was constructed during the Holocene within a large breached caldera formed by collapse of the massive late-Pleistocene Strary Shiveluch volcano. At least 60 large eruptions of Shiveluch have occurred during the Holocene, making it the most vigorous andesitic volcano of the Kuril-Kamchatka arc. Frequent collapses of lava-dome complexes, most recently in 1964, have produced large debris avalanches whose deposits cover much of the floor of the breached caldera. Intermittent explosive eruptions began in the 1990s from a new lava dome that began growing in 1980. The largest historical eruptions from Shiveluch occurred in 1854 and 1964. Source: Kamchatkan Volcanic Eruption Response Team (KVERT) http://www.kscnet.ru/ivs/kvert/index_eng.php ============================================================== To unsubscribe from the volcano list, send the message: signoff volcano to: listserv@xxxxxxx, or write to: volcano-request@xxxxxxxx To contribute to the volcano list, send your message to: volcano@xxxxxxxx Please do not send attachments. ==============================================================
